Many of these small voip providers the voip service is a small portion of their overall business. They may be a small ISP, reselling voip as an add on to internet services. Or they may be a small MSP marketing services to businesses in their area, and VOIP is just one small part of their overall package. If you are already marketing to the customer, providing customer service, billing, and even onsite support, why not add an additional service like VOIP, even if it alone isn't all that profitable? Even if you are only breaking even, having the service in house can save you time and money troubleshooting when a customer call you up and says they are having problems making phone calls and their third party VoIP service support is blaming the network...